外研版高中英语必修一《阅读理解》专项练习题VIP免费

外研版高中英语必修一《阅读理解》专项练习题（含答案） A so-called “smart drug” intended to improve people's cognitive (认知的) function to protect the brain from altitude sickness. Visiting high-altitude sites for work, spot, religious pilgrimages and military can result in cognitive effects, including memory loss and attention difficulties. There's little you can do to prevent these symptoms except acclimatize -but this takes time and doesn't always work. A drug called oxiracetam might be the answer. ShengLi Hu at the Third Military Medical University, Chongqing, China and her colleagues studied the performance of male military personnel at altitude. All lived in towns around 1,800 meters above sea level, During the study, they spent eight days at this altitude and then climbed for three days to reach 4,000 meters, where they stayed for up to a month. Twenty participants took oxriacetam three times a day for the first 15 days of the study, while another 20 received no intervention. The man did tests of attention and memory at the start and end of the study and 20 days in, by which time they had been at 4,000 meters for nine days. While all the participants experienced a drop in cognitive ability at 4,00 meters, those who took oxiracetam showed a much smaller drop than the control group. The team found that at high altitude the brain stem, which plays a critical role in supporting basic living functions, received blood at the expense of areas responsible for more advanced cognitive functions. But in people who took oxiracetam, blood flowing throughout the brain rose,thus offering more oxygen to these areas. This may be how the drug seems to lessen cognitive problems like with low oxygen. It is...